System and method to efficiently clean a blood filter

ABSTRACT

A peritoneal dialysis apparatus includes a filter and a dialysis fluid circuit in fluid communication with the filter. The peritoneal dialysis apparatus also includes a pump for pumping fresh dialysis fluid to a peritoneum of a patient via the dialysis fluid circuit and pumping used dialysis fluid from the peritoneum of the patient through the dialysis fluid circuit and the filter. The peritoneal dialysis apparatus further includes a selective air access in fluid communication with the dialysis fluid circuit and a control unit configured to control the pump during a peritoneal dialysis treatment and a filter cleaning sequence. The control unit forms a fluid mixture during a filter cleaning sequence by opening the selective air access to mix air with a physiologically safe fluid. The fluid mixture is transferred across insides and/or outsides of the filter at least one time.

PRIORITY CLAIM

This application claims priority to and the benefit as a continuationapplication of U.S. patent application Ser. No. 16/673,317, filed Nov.4, 2019, entitled “System and Method to Efficiently Clean a BloodFilter”, which is a continuation of U.S. patent application Ser. No.15/980,387, filed May 15, 2018, entitled “System and Method toEfficiently Clean a Blood Filter”, now U.S. Pat. No. 10,463,775, whichis a continuation of U.S. patent application Ser. No. 13/736,602, filedJan. 8, 2013, entitled “System and Method to Efficiently Clean a BloodFilter”, now U.S. Pat. No. 9,968,723, the entire contents of which areincorporated herein by reference and relied upon.

BACKGROUND

The examples discussed below relate generally to medical fluid delivery.More particularly, the examples relate to systems, methods andapparatuses for the cleaning of blood filters, such as dialyzers orhemofilters.

Many current dialyzers are not reused, they are instead discarded aftera single use. In the event that dialyzers are reused, they are mostoften flushed with copious amounts of water, and/or very strongchemicals to remove residual biological fluids and disinfect themembrane. Dialyzers can alternatively be disinfected with heat,eliminating the need for chemicals but still requiring water. Dialysissystems also require that excess biological residuals be removed fromthe dialyzer periodically. For ecological and cost reasons, andespecially for systems used in the home and for travel, it is desirableto minimize the amount of water used for such cleaning and disinfecting.

An improved blood filter cleaning and disinfecting system and method areneeded accordingly.

SUMMARY

By recirculating fluid in a blood filter, and by injecting air bubblesinto the circuit at opportune times, the efficiency of the cleaningprocedure for the blood filter can be maximized without consuming vastquantities of water.

The examples below describe systems and methods that provide a bloodtreatment for a patient. The blood treatment can be any blood filteringtreatment, such as hemodialysis (“HD”), hemofiltration (“HF”),hemodiafiltration (“HDF”), or continuous renal replacement therapy(“CRRT”). A common thread between these treatments is that an associatedfilter, e.g., hemodialyzer or hemofilter, can be reused. If not reused,the filter is discarded. If reused, the filter needs to be cleaned on aperiodic basis, e.g., between each use. In one embodiment, the systemand method of the present disclosure clean the filter after eachtreatment, just prior to a disinfection sequence in which the treatmentfluid lines and blood lines are cleaned either with hot water or achemical disinfectant. It is contemplated to perform the filter cleaningprocess of the present disclosure after treatment when the blood lineshave been disconnected from the patient and connected together eitherdirectly or via a treatment fluid loop.

One goal of the present disclosure is to clean or rinse the dialyzerwithout using a large amount of fluid, such as dialysate, replacementfluid or saline. Another goal of the present disclosure is to clean orrinse the blood filter effectively. In the system and method describedherein, a volume on the order of 250 ml of dialysate, saline orreplacement fluid may be used to clean the dialyzer. As described indetail below, the dialysate, saline or replacement fluid is reversedback and forth, or pulsed, through the blood filter and combined atopportune times with air to effectively remove blood clots, proteins,residual biological fluids and the like from the filter membranes toclean the filter for future use.

As mentioned above, regardless of the type of machine or therapyemployed, a filter is provided. The filter is connected fluidly to ablood pump so that the blood pump can pump blood through the insides ofthe filter membranes to clean the blood. At least one treatment fluidpump is provided to pump treatment fluid, e.g., dialysate for HD, HDFand CRRT or replacement fluid for HF, HDF and CRRT, to clean the bloodand to remove used treatment fluid from the filter. With HD, forexample, a first treatment fluid pump pumps dialysate to the dialyzer,while a second treatment fluid pump removes used dialysate from thedialyzer. With HF, a first replacement fluid pump pumps replacementfluid directly to the blood tubing connected to a hemofilter, while asecond pump removes used replacement fluid from the hemofilter. WithHDF, the HD configuration is combined with a third pump that pumpsreplacement fluid directly to the blood tubing connected to thehemodialyzer. CRRT can have any of the pumping configurations andperform any of HD, HF or HDF and in general is a slowed or low flowrateversion of the corresponding HD, HF or HDF therapy. CRRT is performed ina hospital setting and typically for acute kidney failure.

Another component of the present disclosure that is provided regardlessof the type of machine or therapy employed is an access to ambient air.The air in one embodiment is introduced on the blood side of the filterso that the air can travel to the blood sides or insides of the filtermembranes. The air can be introduced through an air filter that removescontaminants from the air and cleans the air so as to be suitable forinjecting into the blood circuit, even though the air is eventuallypurged from the entire system, and the circuit is disinfected.

The blood and treatment pumps may be of a type suitable for medicalfluid delivery and are typically peristaltic or volumetric type membraneor diaphragm pumps. The pumps may operate with one or more valve thatselectively opens and closes a line or tube leading to and/or from eachpump. Each of the pumps and valves is controlled automatically by acontrol unit or controller that uses one or more processor and memory.The pumps and valves may be operated pneumatically, electromechanicallyor via some combination thereof. In one embodiment, the controller orcontrol unit operates the pumps and valves according to the followingsequence to clean or rinse the dialyzer.

In a first phase of the sequence, the system and method of the presentdisclosure attempt to loosen blood clots, proteins and biological fluidsfrom the insides of the filter membranes by reversing treatment fluidback and forth (pulsating the fluid) across the insides and/or outsidesof the filter membranes. The reversing of the treatment fluid can bedone via the blood pump, a treatment fluid pump, or both. In thismanner, the insides and/or outsides of the membrane walls are fluidlyscrubbed. And because the same fluid is moved back and forth to suspenddebris within the fluid, and not sent to drain, a relatively smallamount of fluid is actually needed to perform this first phase. Thetreatment fluid that is used can be (i) fresh fluid that has not beenused in the treatment, (ii) leftover treatment fluid pulled from thetreatment fluid circuit or (iii) leftover treatment fluid that has beenused to rinseback blood to the patient at the end of treatment.

The cleaning fluid is in one embodiment a physiologically safe fluid,such as dialysate, replacement fluid or saline. Thus while water couldbe used instead of a physiologically compatible treatment fluid in thisfirst phase, a physiologically compatible fluid is desired because it isthought that pure water would tend to create more new blood clots thanthe physiologically safe fluid. Alternatively, e.g., if the machine isdisinfected after the dialyzer cleaning procedure of the presentdisclosure, the cleaning fluid can be a stronger fluid, such as astronger acid, a stronger base, or enzymatic cleaner, which are goodclot removers.

In a second phase, air is injected into the blood filter from an airaccess, optionally protected by an air filter. The air is pulled intothe treatment fluid creating an air/treatment fluid mixture, which has adifferent consistency and thus scrubbing capability than pure treatmentfluid. The air/treatment fluid mixture is pumped from the bottom of thefilter to the top of the filter at least one time. If the air access isarranged such that air must enter the filter from its top, then thesystem and method of the present disclosure first pushes theair/treatment fluid mixture to the bottom or past the bottom of thefilter, and then reverses pumping so as to move the air/treatment fluidmixture up from the bottom of the filter, through the filter. Doing socreates microbubbles (or effervescence) that helps to further removeblood from the dialyzer. As the microbubbles move through the smalldiameter of the filter fibers, the bubbles expose blood particles toalternating phases of liquid and gas, as well as a high shear stress andturbulence at the boundary layer between the two phases, causingenhanced removal from the filter wall.

In a third phase, the system and method of the present disclosureperform a depriming procedure by pulling more air in from the filteredair access. Doing so pushes the air/treatment fluid mixture, now filledwith suspended blood particles including blood clots and proteins, todrain. It should be appreciated that in one embodiment, it is not untilthis third phase that any fluid is discarded from the system. In variousembodiment, phases two, three, and four can be successively repeated toachieve better cleaning, e.g., at the cost of higher water consumption.

In a fourth phase, the blood and treatment fluid circuits are primed,e.g., with purified water or other fluid not contaminated with bloodparticles from the previous step. The priming removes any of thetreatment fluid or air/treatment fluid mixture remaining in eithercircuit, sending same to drain. Once primed with water, it iscontemplated for the system to run a hot water or chemical disinfectionsequence. The disinfection sequence cleans the entire system includingthe treatment fluid lines, the blood lines and the filter. Thedisinfection fluid or water may then be discarded and replaced withfiltered air, leaving the machine disinfected, dry and ready to performanother treatment.

While the present disclosure is described primarily in connection with adialysis machine that reuses the same dialyzer over multiple treatments,e.g., around thirty treatments, the concepts discussed herein are notlimited to such an application. For example, the apparatus andmethodology could be used on a dialyzer cleaning machine. Here, thedialyzer is removed from the dialysis machine after treatment, broughtto the dialyzer cleaning machine, which uses the structure andmethodology discussed herein to clean the dialyzer, which is thenbrought back to the dialysis machine for reuse.

Further, while the present disclosure is described primarily inconnection with a hemodialysis or blood machine, the present disclosureis equally applicable to a dialysis machine that uses a filter to cleana peritoneal dialysis fluid or (“PD”) solution. In such case, the bloodcircuit below is replaced with a peritoneal dialysis circuit that pumpsPD solution into and out of the patient's peritoneum.

It is therefore an advantage of the present disclosure to provide animproved renal failure therapy system and method.

Another advantage of the present disclosure is to provide an improvedblood filter cleaning system and method.

A further advantage of the present disclosure to provide an improvedblood filter cleaning system and method that does not require a largeamount of fluid to clean the blood filter.

It is still another advantage of the present disclosure to provide aneffective blood filter cleaning system and method.

Additional features and advantages are described herein, and will beapparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is schematic illustration of one system configured and arrangedto perform a filter cleaning procedure of the present disclosure.

FIG. 2 is a process flow diagram illustrating one method for cleaning afilter of the present disclosure.

DETAILED DESCRIPTION HD/HF/HDF/CRRT/PD Systems and Methods

Referring now to the drawings and in particular to FIG. 1 , oneembodiment for a system and method of the present disclosure isillustrated by system 10. System 10 includes a blood circuit 20 and atreatment fluid circuit 40. Blood circuit 20 includes an arterial line22 and a venous line 24. Arterial line 22 ends with an arterial needleconnector A. Venous line 24 ends with a venous needle connector V.During treatment, arterial needle connector A connects to an arterialneedle or other access (e.g. a catheter), which is inserted into thepatient for treatment. Venous needle connector V connects to a venousneedle or other access (e.g. a catheter), which is inserted into thepatient for treatment. After treatment, the arterial needle connector Acan be connected to the venous needle connector V, as illustrated inFIG. 1 , for the cleaning process described below. Alternatively, thearterial needle connector A and the venous needle connector V can beplugged into the treatment fluid circuit 40 at mating connectors markedA and V, respectively, after treatment for the cleaning processdescribed below.

Venous line 24 includes a bubble trap or air trap that removes air fromthe blood before being returned to the patient via the venous line.Arterial line 22 includes a blood pump 28 in the illustrated embodiment.Blood pump 28 can be a peristaltic, electrically driven blood pump. Inthe illustrated embodiment, however, blood pump 28 is a volumetric ordiaphragm type pump that operates with an upstream valve 28 a and adownstream valve 28 b. During operation, upstream valve 28 a is opened,downstream valve 28 b is closed, while pump diaphragm 28 c is retractedto pull blood or other fluid into blood pump 28. In the next stroke,upstream valve 28 a is closed, downstream valve 28 b is opened, whilepump diaphragm 28 c is pushed out to likewise push blood or other fluidfrom blood pump 28.

Blood pump 28 pushes blood through a blood filter 30, such as a dialyzerfor hemodialysis (“HD”) of hemodiafiltration (“HDF”), or a hemofilterfor hemofiltration (“HF”). Any of HD, HDF, and HF may be performed forcontinuous renal replacement therapy (“CRRT”). Filter 30 as mentionedabove may also be a filter used for filtered peritoneal dialysis (“PD”).In any case, blood filter 30 has a blood side 30 a and treatment fluidside 30 b separated by a plurality of hollow fiber membranes 30 c(modeled as a single line in FIG. 1 ). The insides of the hollow fibermembranes 30 c form the blood side 30 a, while the treatment fluid side30 b of blood filter 30 is formed between the outsides of hollow fibermembranes 30 c and the inner surface of the housing of blood filter 30.In the illustrated embodiment, blood or other fluid flows into bloodfilter 30 at its top end 30 d, through blood side 30 a, and out of bloodfilter 30 at its bottom end 30 e. The arterial and venous lines 22 and24 can be reversed alternatively, such that blood flow during treatmentflows from bottom end 30 e of blood filter 30, through the filter, andout its top end 30 d.

A saline and/or a replacement fluid source 32 may be provided.Replacement fluid is provided if HDF or HF is performed duringtreatment. Replacement fluid is an injectable quality, physiologicallycompatible fluid that is introduced directly into blood circuit 20, hereillustrated at arterial line 22, but alternatively or additionallyinjected at venous line 24. Saline is used in many dialysis systems forpriming. In the illustrated embodiment, a replacement fluid and/orsaline pump 34 pumps replacement fluid and/or saline as needed intoarterial line 22. Pump 34 can be a peristaltic pump or alternatively bea volumetric or diaphragm type pump, as is illustrated, which operateswith an upstream valve 34 a and a downstream valve 34 b in the samemanner as described above for the volumetric version of blood pump 28.

A heparin supply 36 is provided in the illustrated embodiment. A heparinpump 38 pumps heparin as needed into arterial line 22. Pump 38 canlikewise be a peristaltic pump or alternatively be a volumetric ordiaphragm type pump, as is illustrated, which operates with an upstreamvalve 38 a and a downstream valve 38 b in the same manner as describedabove for the volumetric version of blood pump 28. Heparin from supply36 helps to prevent blood clots in blood circuit 20 and filter 30 as isknown.

Treatment fluid circuit 40 makes treatment fluid, e.g., dialysate,online in one embodiment by accepting purified water from a purifiedwater source (not illustrated). Purified water is delivered to an onlinetreatment fluid generation unit 42 in the illustrated embodiment. Onlinetreatment fluid generation unit 42 mixes the purified water with acidand bicarbonate concentrates to make a solution that is physiologicallycompatible with the patient's blood. One suitable online treatment fluidgeneration unit 42 is described in U.S. Patent Publication No.2009/0008331, which published Jan. 8, 2009, entitled, “HemodialysisSystems and Methods”, the entire contents of which are incorporatedherein by reference and relied upon.

A to-filter pump 44 pumps treatment fluid from online treatment fluidgeneration unit 42, through a pathogen filter 46, such as anultrafilter. Pump 44 is illustrated as being a peristaltic pump but isalternatively a volumetric diaphragm pump, like pumps 28, 34 and 38.Taking purified, e.g., ultrapure water, turning it into treatment fluidor dialysate and passing the treatment fluid through an ultrafilterproduces a solution at or near injectable or drug infusion quality. Pump44 pulls the dialysate through an online heater 48 that heats thedialysate to approximately body temperature or 37° C. Heater 48 isprovided for patient comfort and can be removed from treatment fluidcircuit 40 if desired.

Pump 44 delivers fresh treatment fluid, e.g., dialysate, under positivepressure to treatment fluid side 30 b of blood filter 30. Duringtreatment, treatment fluid, e.g., dialysate, cleans the blood flowing(e.g., countercurrent) through the blood side 30 a of blood filter 30. Afrom-filter pump 50 pulls spent or used dialysate from treatment fluidside 30 b of blood filter 30 and delivers same to drain. Pump 50 isillustrated as being a peristaltic pump but is alternatively avolumetric diaphragm pump, as illustrated by pumps 28, 34 and 38. Ifprovided as a volumetric diaphragm pump, it is contemplated to use pump50 to push spent or used dialysate under positive pressure tofrom-filter pump 50 during its fill stroke. In this manner, treatmentfluid is never under negative pressure within blood filter 30, which cancause air to come out of solution. Although not illustrate, one or moreair trap can be located upstream of down stream of to-filter pump 44.

Also not illustrated, treatment fluid circuit 40 in one embodimentincludes balance chambers that balance or make equal the amount of freshtreatment fluid that is delivered to blood filter 30 with spent or usedfluid that is removed from blood filter 30, which prevents increasing ordecreasing the amount of fluid present within the patient. The operationof the balance chambers is known to those of skill in the art but ingeneral involves a known volume chamber that is divided by a diaphragmmuch like a diaphragm pump. The chamber on one side of the diaphragmreceives spent treatment fluid, which moves the diaphragm to dispel alike amount of fresh treatment fluid. In a next stoke, the chamber onthe other side of diaphragm receives fresh treatment fluid, which movesthe diaphragm to dispel a like amount of spent treatment fluid and soon. Two balance chambers may be used out of phase with one another sothat there is always some fresh fluid flow to blood filter 30 and somespent or used fluid flow from blood filter 30.

With fresh and spent treatment fluid being balanced, an ultrafiltrate(“UF”) pump 52 is provided to remove a precise amount of additionalfluid from the patient over the course of treatment. UF Pump 52 isillustrated as being a peristaltic pump but is alternatively avolumetric diaphragm pump, like pumps 28, 34 and 38. UF Pump 52 pulls anamount of UF off of the patient over the course of treatment in anattempt to return the patient to his or her dry weight.

A control unit 60 is provided, which can include one or more processorand one or more memory. Control unit 60 runs one or more computerprogram including one or more computer programs to implement method 100illustrated in FIG. 2 . The processing and memory of control unit 60also operate with a user interface (not illustrated), which enables auser to interact with and control system 10. Control unit 60 controlsvia electrical signals (dotted lines) the electrically drivenperistaltic pumps, such as pumps 44, 50 and 52, and heater 48. Controlunit 60 can also control online treatment fluid generation unit 42 usingelectrical signals (dotted lines) and/or pneumatic signals (dashedlines) as illustrated. Control unit 60 also controls via electricalsignals (dotted lines) each of a plurality of pneumatic valves 70 a, 70b, 70 c, 70 d . . . 70 n, which in turn control pneumatic signals(dashed lines) running to diaphragm pumps, such as pumps 28, 34 and 38and fluid valves, such as fluid valves 28 a, 28 b, 34 a, 34 b, 38 a, 38b.

One or more of pneumatic valves 70 a, 70 b, 70 c, 70 d . . . 70 n alsocontrols pneumatic signals (dashed lines) running to an air valve 18.Air valve 18 allows air filtered by a filter 16, such as ahigh-efficiency particulate air (“HEPA”) filter, to be pumped intosystem 10 via heparin pump 38. It should be appreciated that whilefiltering the air is preferred, the air does not have to be filtered forthe present disclosure, for example, if system 10 is to be disinfected.In an embodiment, negative pressure exerted on heparin vial 36 viaheparin pump 38 is relieved by opening air valve 18 and allowing air toenter via filter 16 and heparin vial 16 to atmosphere pressure.

In an embodiment, each of pneumatic valves 70 a, 70 b, 70 c, 70 d . . .70 n communicates fluidly with a positive pressure source 72 and anegative pressure source 74. In this manner pneumatic valves 70 a, 70 b,70 c, 70 d . . . 70 n can supply positive pressure from source 72 to afluid valve (e.g., to close the valve) or negative pressure from source74 to the fluid valve (e.g., to open the valve). Likewise, valves 70 a,70 b, 70 c, 70 d . . . 70 n can supply positive pressure from source 72to a fluid pump (e.g., to pump fluid out of the pump) or negativepressure from source 74 to the fluid pump (e.g., to pull fluid into thefluid pump).

Referring now to FIG. 2 , one embodiment of a dialyzer cleaning methodoperated under the control of control unit 60 is illustrated by method100. Method 100 begins at oval 102. At block 104 treatment under system10 ends. The treatment can be any type of blood cleansing treatment,such as hemodialysis (“HD”), hemofiltration (“HF”), hemodiafiltration(“HDF”), and continuous renal replacement therapy (“CRRT”). The end oftreatment for system 10 typically involves a blood rinseback to thepatient. So that the patient does not lose blood because of thetreatment, the blood at the end of treatment is pushed back to thepatient. In one embodiment, treatment fluid, such as dialysate, is usedto push the blood back through arterial line 22 and venous line 24 tothe patient. Alternatively, replacement fluid or saline from source 32is used to push the blood back through arterial line 22 and venous line24 to the patient.

At block 106, the patient after blood rinseback disconnects arterialline 22 and venous line 24 from their respective needles and either (i)connects arterial line 22 and venous line 24 together (e.g., using aseparate recirculation connector to connect arterial needle connector Ato venous needle connector V) or (ii) connects arterial needle connectorA to corresponding port A in treatment fluid circuit 40 and venousneedle connector V to corresponding port V in treatment fluid circuit40.

In an embodiment, method 100 transitions automatically from block 106 toblock 108 after arterial and venous lines 22 and 24 are connectedtogether or to treatment fluid circuit 40. In an alternative embodiment,method 100 transitions from block 106 to block 108 at the end oftreatment and needle disconnection via one or more user input using userthe interface (not illustrated) into control unit 60.

At block 108, system 10 causes fluid to be moved back and forth, e.g.,vigorously, to remove blood clots, proteins and/or residual biologicalfluids from the membranes of blood filter 30. In an embodiment, bloodpump 28 is used to pulsate treatment fluid, replacement fluid or salineback and forth across the insides of the membranes of blood filter 30.To do so, membrane 28 c is sucked and pushed back and forth in time withthe sequencing of valves 28 a and 28 b. If blood pump 28 is aperistaltic pump, the pump rotor is rotated in alternating directions.In an embodiment, blood pump 28 cycles approximately 50 to 300milliliters (“ml”), e.g., 250 ml, of treatment fluid, replacement fluidor saline back and forth across the insides of the membranes of bloodfilter 30 approximately twenty times or cycles over a period of aboutfive to twenty, e.g., fifteen, minutes.

Alternatively or additionally, one or both treatment fluid pumps 44 and50 is used to pulsate treatment fluid, replacement fluid or saline backand forth across the outsides of the membranes of blood filter 30. To doso, the rotors of pumps 44 and 50 are rotated in alternative directions.If pumps 44 and 50 are instead volumetric diaphragm pumps, theassociated pump diaphragms and valves are sequenced and cycled asdescribed above for blood pump 28. If treatment pumps 44 and/or 50 isused, treatment fluid pumps 44 and 50 can cycle approximately 50 to 300ml, e.g., 250 ml, of treatment fluid, replacement fluid or saline backand forth across the outsides of the membranes of blood filter 30,again, approximately twenty times or cycles over a period of about fiveto twenty, e.g., fifteen, minutes.

Running blood pump 28 in combination with one or both treatment pumps 44and 50 may desirably balance the pressures on both sides of 30 a and 30b of membranes 30 c during one or both of the operations discussed inconnection with blocks 108 and 110. Or, it may be desirable to maintaina pressure gradient across membranes 30 c, e.g., maintaining side 30 aat a higher pressure than side 30 b. The gradient may be accomplished byrunning blood pump 28 only, or by running blood pump 28 at a higherpressure than that at which treatment fluid pump 44 and 50 are operated.

In an embodiment, treatment fluid, such as dialysate, already resides inboth blood side 30 a and treatment fluid side 30 b of blood filter 30from the end of treatment rinseback procedure. It is accordingly logicalto use the already present treatment fluid for the pulsating cleansingof block 108. Treatment fluid, such as dialysate, is physiologicallysafe and tends not to clot or lyse blood in comparison with purifiedwater.

If instead saline resides in one or both of blood side 30 a andtreatment fluid side 30 b of blood filter 30 due to an end of treatmentor rinseback procedure, it is logical to use the already present salinefor the pulsating cleansing of block 108 (for one or both of blood side30 a and treatment fluid side 30 b). Saline is likewise physiologicallysafe and tends not to clot or lyse blood in comparison with purifiedwater.

If instead replacement fluid resides in one or both of blood side 30 aand treatment fluid side 30 b of blood filter 30 due to an end oftreatment or rinseback procedure, it is logical to use the alreadypresent replacement fluid for the pulsating cleansing of block 108 (forone or both of blood side 30 a and treatment fluid side 30 b).Replacement fluid is likewise physiologically safe and tends not to clotor lyse blood in comparison with purified water.

In alternative embodiments, system 10 pulls treatment fluid, e.g.,dialysate or replacement fluid, from a source or storage tank of same.System 10 can pull saline from supply 32, pull replacement fluid fromsupply 32 or pull dialysate from a holding tank (not illustrated in FIG.1 ). The pulled physiologically safe fluid is driven into treatmentfluid site 30 b of blood filter 30, across membranes 30 c, into bloodside 30 a of blood filter 30 and into blood circuit 20. In anembodiment, about 50 to 300 ml (e.g., 250 ml) of such fluid is pulledand used for the pulsating cleansing of the blood filter membranes ofblock 108. In any case, because the fluid used to loosen blood clots andproteins from the membrane walls of blood filter 30 is pulsed back andforth and is not sent to drain, no fluid is consumed at block 108.

At block 110, air is injected into blood circuit 20 and blood side 30 aof blood filter 30, where it produces an air/treatment fluid (e.g.,air/dialysate) mixture. The air/treatment fluid is pumped in oneembodiment so that the mixture enters bottom end 30 e of blood filter30, which may require that the air/treatment fluid mixture first bepumped down the blood filter 30 and then reversed up and out top end 30d of the blood filter 30 depending upon how, as discussed above, bloodlines 22 and 24 are connected to blood filter 30. The air treatmentmixture can be circulated through the entire blood circuit 20 and/ortreatment fluid circuit 40 one or more time. Pumping the treatment fluidup from the bottom 30 c of blood filter 30 forces the air throughmembranes 30 c and breaks the air into microbubbles (e.g.,effervescence), which helps to remove residual blood, e.g., clots,proteins and biological fluids from blood filter 30. In particular, theeffervescent effect is believed to create areas of high shear stressesand turbulence at various air/water interfaces of the surfaces ofmembranes 30 c, which assists in loosening blood residuals.

In an embodiment, air valve 18 is opened and heparin pump 38, includingthe cycling of fluid valves 38 a and 38 b (or blood pump 28), is used topull either air as needed, or a known and desired amount of air, e.g.,25 ml, into blood circuit 20 and blood side 30 a of blood filter 30.Here, heparin vial 36 may be empty or removed so that heparin is notinjected into the blood lines along with the air. Or, an additionalheparin valve (not illustrated) can be provided to isolate heparin vial36 from the air line. Still further alternatively, heparin enteringblood circuit 20 is tolerated. And again, any air entering system 10 viaair valve 18 and heparin pump 38 is filtered first via filter 16.

Blood pump 28 is used to pump the air/treatment fluid along filter 30(e.g., from top to bottom) and throughout blood circuit 20. Ifconnectors A and V of blood lines 22 and 24 are plugged into treatmentfluid circuit 40, then blood pump 28 can be used to pump air/treatmentfluid through treatment fluid circuit 40 as well. Otherwise, treatmentfluid pumps 44 and 50 may be used alternatively or additionally to pumpair/treatment fluid through treatment fluid circuit 40. In either case,it is contemplated to alternatively or additionally scrub the outside ofmembranes 30 c of blood filter 30 by passing the air/treatment fluidmixture through to the treatment fluid side 30 b of blood filter 30.

Although not illustrated, a second air vent valve 18 and second, e.g.,HEPA, filter 16 can be placed in treatment fluid circuit 40. Forexample, a second air trap 26 can be placed between heater 48 and pump44 to trap air caused by the heating of the treatment fluid. Second airvent valve 18 and second filter can then be coupled to the upper or aircollection portion of air trap 26.

At block 110, it is contemplated for system 10 and control unit 60 toalternatively or additionally pull air into treatment fluid circuit 40by opening second air valve 18 and operating treatment fluid pump 44and/or treatment fluid pump 50 to circulate air/treatment fluid intotreatment fluid side 30 b to scrub the treatment fluid side 30 b ofblood filter 30 including the outsides of membranes 30 c.

Air/treatment fluid may be pulsed back and forth along the insidesand/or outsides of the membranes 30 c or be flowed around and aroundform top end 30 d to bottom end 30 e of blood filter 30 a plurality oftimes. Air/treatment fluid has a different consistency and shearingeffect than does pure liquid, which is believed to provide goodparticulate loosening in combination with the pure treatment fluid,e.g., dialysate, saline or replacement fluid. It should be appreciatedthat no dialysate, saline or replacement fluid is sent to drain duringthe step of block 110, just as with block 108.

At diamond 112, method 100 determines whether the steps at blocks 108and 110 are to be repeated. If so, method 100 returns to block 108.Here, pure dialysate, saline or replacement fluid may need to be pulledfrom a source or holding tank to repeat the step of block 108. Theoperational loop between block 108 and diamond 112 may be repeated anydesired number of times. If method 100 determines that the steps atblocks 108 and 110 are not to be repeated, method 100 proceeds to block114. It is contemplated to use different methodologies for determiningwhen the steps at blocks 108 and 110 are repeated e. The number ofrepeats can be set in memory as a preset number. The number of repeatscan be set as part of a device prescription that is patient specific.The number of repeats can alternatively or additionally be based onother factors, such as one or more of a pressure reading, a bundlevolume measurement of the dialyzer, the results of a dialyzer clearancetest, the age of the dialyzer (how many uses), for example. It isexpressly contemplated therefore that even for the same patient, thenumber of repeats at diamond 112 may vary from treatment to treatment.

At block 114, air valve 18 is or continues to be opened and heparin pump38 including the cycling of fluid valves 38 a and 38 b are used to pullair into blood circuit 20 and blood side 30 a of blood filter 30 topurge the blood circuit 20 of all liquid. Again, heparin vial 36 may beempty or removed so that heparin is not injected along with air. Oragain, an additional heparin valve (not illustrated) can be provided toisolate heparin vial 36 from the air line. And again, any air enteringsystem 10 via air valve 18 and heparin pump 38 is filtered first viafilter 16.

Blood pump 28 can be used to push air/treatment fluid, now loaded withblood residuals, through the filter membranes, into treatment fluid side30 b of blood filter 30, from there into treatment fluid circuit 40, andeventually to drain. If connectors A and V of blood lines 22 and 24 areplugged into treatment fluid circuit 40, then blood pump 28 can be usedadditionally or alternatively to pump air to push air/treatment fluid,now loaded with blood residuals, directly into treatment fluid circuit40 and out the drain.

At diamond 116, method 100 determines whether the steps at blocks 108 to114 are to be repeated. If so, method 100 returns to block 108. Hereagain, pure dialysate, saline or replacement fluid may need to be pulledfrom a source or holding tank to repeat the step of block 108. Theoperational loop between block 108 and diamond 116 may be repeated anydesired number of times. If method 100 determines that the steps atblocks 108 to 114 are not to be repeated, method 100 proceeds to block118.

At block 118, system 10 performs a prime/disinfection procedure to cleanthe entire system including blood circuit 20 and dialysate circuit 40.Hot water or a chemical solution may be used to prime and disinfect thesystem. The hot water or chemical solution aids in forcing any remainingblood residuals, e.g., clots or proteins, to drain. The disinfectionfluid may be left inside system 10 until the next use or purged againvia filtered air so that system 10 is left in a dry condition until thenext treatment.

At oval 120, method ends.

As mentioned above, while the present disclosure is described primarilyin connection with a blood therapy, e.g., dialysis, machine that reusesthe same blood filter 30 over multiple treatments, e.g., around thirtytreatments, the concepts discussed herein are not limited to such anapplication. The apparatus and methodology described herein could beused instead on a dialyzer cleaning machine for example. Here, bloodfilter 30 is removed from the blood therapy machine after eachtreatment, brought to the dialyzer cleaning machine, which uses thestructure and methodology discussed herein to clean blood filter 30,which is then brought back to the blood therapy machine for reuse.

Also mentioned above, while the present disclosure is describedprimarily in connection with a blood therapy machine, the presentdisclosure is equally applicable to a dialysis machine that uses afilter to clean a peritoneal dialysis fluid or (“PD”) solution. In suchcase, the blood circuit 20 described herein is replaced with aperitoneal dialysis fluid circuit that pumps PD solution into and out ofthe patient's peritoneum and through the insides of the membranes of aPD filter 30. Here, heparin pump 38 and heparin are not needed.Treatment fluid circuit 40 could remain substantially unchanged and pumponline or bagged dialysate through PD filter 30 over the outsides of themembranes of the filter to clean the sterile solution returning from thepatient's peritoneum.

Additional Aspects of the Present Disclosure

Aspects of the subject matter described herein may be useful alone or incombination with any one or more of the other aspect described herein.Without limiting the foregoing description, in a first aspect of thepresent disclosure, a method for cleaning a blood filter includes:pumping a physiologically safe fluid back and fourth through the insidesand/or the outsides of a plurality of hollow fiber membranes of theblood filter to remove or loosen blood residuals, such as blood clots,proteins and/or biological fluid; injecting air into the physiologicallysafe fluid to form an air/fluid mixture; pumping the air fluid mixturethrough the insides and/or outsides of the plurality of the hollow fibermembranes of the blood filter to further or remove or loosen bloodresiduals therefrom; and removing the air/physiologically safe fluidmixture along with the removed or loosened blood residuals to drain.

In accordance with a second aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, pumping the air/physiologically safe fluid mixturethrough the insides and/or outsides of the membranes includes breakingthe air into microbubbles.

In accordance with a third aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, pumping the air/physiologically safe fluid mixturethrough the insides and/or outsides of the membranes includes pumpingthe mixture from a bottom of the blood filter to a top of the bloodfilter.

In accordance with a forth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, pumping the air/physiologically safe fluid mixturethrough the insides and/or outsides of the membranes includes pumpingthe air/physiologically safe fluid mixture back and forth across themembranes.

In accordance with a fifth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, pumping the air/physiologically safe fluid mixturethrough the insides and/or outsides of the membranes includescirculating the air/physiological safe fluid across the membranes aplurality of times.

In accordance with a sixth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, removing the air/physiologically safe fluid mixture todrain includes injecting air to push the mixture to drain.

In accordance with a seventh aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, the method further includes priming or disinfecting theblood filter after removing the air/physiologically safe fluid mixtureto drain.

In accordance with an eighth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, injecting air includes filtering the air.

In accordance with a ninth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, injecting air includes pumping air into the blood filtervia a blood pump.

In accordance with a tenth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, pumping the physiologically safe fluid back and forthincludes reversing a blood pump.

In accordance with an eleventh aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, pumping the physiologically safe fluid back andforth includes sequencing a plurality of valves.

In accordance with a twelfth aspect of the present disclosure, which maybe used in combination with any other aspect or combination of aspectslisted herein, the method includes transferring the physiologically safefluid from outside of the hollow fiber membranes, through walls of themembranes, and into the insides of the membranes to pump the treatmentfluid back and forth.

In accordance with a thirteenth aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, the physiologically safe fluid used for pumpingback and forth through the insides of the membranes is provided via arinseback of blood to the patient, leaving physiologically compatiblefluid inside of the membranes.

In accordance with a fourteenth aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, the physiologically safe fluid is selected fromthe group consisting of: dialysate, replacement fluid and saline.

In accordance with a fifteenth aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, the method is used with renal therapy equipment.

In accordance with a sixteenth aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, the blood filter is a dialyzer.

In accordance with a seventeenth aspect of the present disclosure, whichmay be used in combination with any other aspect or combination ofaspects listed herein, a renal therapy system includes: a blood filterincluding a plurality of hollow fiber membranes; arterial and venouslines in fluid communication with the blood filter; a blood pump forpumping blood through the arterial and venous lines and the bloodfilter; a treatment fluid pump in fluid communication with (a) atreatment fluid side of the blood filter or (b) the arterial or venousline; and a control unit controlling the blood pump and the treatmentfluid pump during treatment and at least one of the blood pump and thetreatment pump during a filter cleaning sequence in which (i) aphysiologically safe fluid is transferred back and forth across theinsides and/or outsides of the plurality of hollow fiber membranes, (ii)the physiologically safe fluid mixed with air is transferred across theinsides and/or outsides of the plurality of hollow fiber membranes atleast one time, and (iii) the physiologically safe fluid mixed with airand blood residuals loosened or removed from the hollow fiber membranesis transformed to drain.

In accordance with an eighteenth aspect of the present disclosure, whichmay be used with the seventeenth aspect in combination with any otheraspect or combination of aspects listed herein, the system furtherincludes a filtered air access in fluid communication with the bloodpump, and a valve, the control unit controlling the valve to selectivelyallow in the air to be mixed in (ii).

In accordance with a nineteenth aspect of the present disclosure, whichmay be used with the seventeenth aspect in combination with any otheraspect or combination of aspects listed herein, the treatment fluid pumpis a replacement fluid pump, the treatment fluid being replacementfluid.

In accordance with a twentieth aspect of the present disclosure, whichmay be used with the nineteenth aspect in combination with any otheraspect or combination of aspects listed herein, the control unitcontrols the replacement fluid pump to perform at least one of (i), (ii)or (iii).

In accordance with a twenty-first aspect of the present disclosure,which may be used with the seventeenth aspect in combination with anyother aspect or combination of aspects listed herein, the treatmentfluid pump is a fresh dialysate fluid pump, and wherein the treatmentfluid is dialysate.

In accordance with a twenty-second aspect of the present disclosure,which may be used with the seventeenth aspect in combination with anyother aspect or combination of aspects listed herein, the systemincludes a saline supply in fluid communication with the arterial orvenous line, the treatment fluid pump being a saline pump, and thephysiologically safe fluid being saline.

In accordance with a twenty-third aspect of the present disclosure,which may be used with the seventeenth aspect in combination with anyother aspect or combination of aspects listed herein, the control unitis configured to cause the blood pump to perform (i) to (iii) and thetreatment fluid pump to be operated during at least one of (i) and (ii)on the outsides of the hollow fiber membranes to attempt to equalizepressures across the hollow fiber membranes.

In accordance with a twenty-fourth aspect of the present disclosure,which may be used with the seventeenth aspect in combination with anyother aspect or combination of aspects listed herein, the control unitis configured to cause the blood pump only to perform (i), (ii) and(iii).

In accordance with a twenty-fifth aspect of the present disclosure,which may be used with the seventeenth aspect in combination with anyother aspect or combination of aspects listed herein, the control unitis configured to cause the blood pump and the treatment fluid pump toperform (i) and (ii) and the blood pump only to perform (iii).

In accordance with a twenty-sixth aspect of the present disclosure, anyof the structure and functionality illustrated and described inconnection with FIGS. 1 and 2 may be used in combination with any otheraspect or combination of aspects listed herein.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows: 1: A peritoneal dialysis apparatuscomprising: a filter including a plurality of hollow fiber membranes; adialysis fluid circuit in fluid communication with the filter; a pumpfor pumping fresh dialysis fluid to a peritoneum of a patient via thedialysis fluid circuit, and used dialysis fluid from the peritoneum ofthe patient through the dialysis fluid circuit and the filter; aselective air access in fluid communication with the dialysis fluidcircuit; and a control unit configured to control the pump during aperitoneal dialysis treatment and a filter cleaning sequence in which(i) a physiologically safe fluid is transferred across insides and/oroutsides of the plurality of hollow fiber membranes at least one time,(ii) a fluid mixture is formed by opening the selective air access tomix air with the physiologically safe fluid, and (iii) the fluid mixtureis transferred across the insides and/or outsides of the plurality ofhollow fiber membranes at least one time, wherein the filter cleaningsequence is performed such that the fluid mixture is delivered to thefilter instead of a drain. 2: The apparatus of claim 1, wherein thephysiologically safe fluid includes fresh dialysis fluid. 3: Theapparatus of claim 1, wherein the fresh dialysis fluid is (i) preparedfrom an online source, or (ii) received from a fluid container. 4: Theapparatus of claim 1, wherein the pump is configured to pull the air infrom outside the selective air access for mixing with thephysiologically safe fluid. 5: The apparatus of claim 1, wherein thefluid mixture is configured to enhance loosening or removing residualsfrom the hollow fiber membranes. 6: The apparatus of claim 1, furthercomprising an air-passing filter in fluid communication with theselective air access and configured to filter air passing through theselective air access. 7: The apparatus of claim 1, wherein the selectiveair access is at least one of (a) vented via a protective membrane or(b) selectively accessed via a valve. 8: The apparatus of claim 1, wherein the physiologically safe fluid includes saline provided by a salinesupply in fluid communication with the dialysis fluid circuit, andwherein the pump or a second pump is positioned and arranged to pumpsaline from the saline supply. 9: The apparatus of claim 1, wherein thecontrol unit is configured to cause the pump to perform at least (i) and(iii) and a second pump to be operated simultaneously in an attempt toequalize pressure across the hollow fiber membranes. 10: The apparatusof claim 1, wherein the control unit is configured to cause the pump toperform at least (i) and (iii), and use a second pump to perform (ii).11: The apparatus of claim 1, wherein the control unit is configured tocause the pump to perform (ii) and a second pump to perform (i) and(iii). 12: The apparatus of claim 1, wherein the filter is a dialyzer.13: The apparatus of claim 1, wherein the control unit is configured tocause the physiologically safe fluid to be transferred back and forthacross the plurality of hollow fiber membranes a plurality of timesbefore mixing the physiologically safe fluid with the air. 14: Theapparatus of claim 1, which is configured to transfer the fluid mixtureto the drain after (iii). 15: The apparatus of claim 1, wherein thecontrol unit is configured to perform (iii) such that the fluid mixtureis mixed with dialysis fluid instead of being purged to the drain. 16: Amethod for cleaning a filter during a cleaning sequence comprising: (i)pumping a physiologically safe fluid across insides and/or outsides of aplurality of the hollow fiber membranes of a filter for peritonealdialysis; (ii) forming a fluid mixture by injecting air into thephysiologically safe fluid; (iii) during the cleaning sequence, pumpingthe fluid mixture across the insides and/or outsides of the plurality ofthe hollow fiber membranes of the filter so as to remove or loosenresiduals, such as proteins and/or biological fluid, wherein the fluidmixture is delivered to the filter instead of a drain during at least(ii) and (iii); and (iv) transferring the fluid mixture along with theremoved or loosened residuals to the drain, wherein the use of the fluidmixture enables the cleaning sequence to be performed after a peritonealdialysis treatment. 17: The method of claim 16, wherein pumping thefluid mixture across the insides and/or outsides of the membranesincludes at least one of (a) breaking the air into microbubbles, (b)pumping the fluid mixture from a bottom of the filter to a top of thefilter, (c) pumping the fluid mixture back and forth across themembranes, or (d) circulating the fluid mixture across the membranes aplurality of times. 18: The method of claim 16, wherein thephysiologically safe fluid is pumped back and forth across the insidesand/or the outsides of the plurality of hollow fiber membranes of thefilter so as to remove or loosen the residuals. 19: The method of claim16, wherein transferring the fluid mixture to the drain includesinjecting air to push the fluid mixture along with the removed orloosened residuals to the drain. 20: The method of claim 16, whichfurther includes at least one of: priming the filter with at least oneof dialysis fluid, replacement fluid, or saline after the transferringperformed in (iv); or disinfecting the filter with at least one of hotwater or a chemical disinfectant after the transferring performed in(iv). 21: The method of claim 16, wherein the cleaning sequence isperformed at the end of the peritoneal dialysis treatment whenperitoneal dialysis fluid is pumped from a patient's peritoneum. 22: Themethod of claim 16, wherein injecting air includes at least one of (a)filtering the air or (b) pumping the air into the filter via a pump.